js用rgb标签随机颜色

let tags = document.getElementById("tags").getElementsByTagName("a");    
for(let i in tags){    
    let r = Math.floor(Math.random()*256);    
    let g = Math.floor(Math.random()*256);    
    let b = Math.floor(Math.random()*256);    
    tags[i].style.background = 'rgba('+r+','+g+','+b+')';    
}